Organisations should favour short-lived tokens for agents because agentic work is task-based and often context-specific. Long-lived credentials widen the window for misuse, make attribution weaker, and encourage identity reuse across sessions or tasks. For sensitive actions, re-authentication tied to execution context is stronger than session-start trust.
Why short-lived tokens fit agent workloads better
Agent access should be treated as execution-bound, not session-bound. Short-lived tokens fit that model because the authority expires with the task, reducing the time an exposed credential remains useful and making each action easier to attribute to a specific run, tool call, or approval event. That is especially important when agents act across multiple systems or change context frequently.
Long-lived credentials create a larger blast radius because they stay valid after the original task, conversation, or operator intent has moved on. They also encourage reuse across sessions, which weakens separation between runs and makes it harder to tell whether an action came from the intended agent instance, a reused token, or a later compromise.
For reference, the difference between static and ephemeral credential patterns is a recurring NHI control theme in Ultimate Guide to NHIs — Static vs Dynamic Secrets, which aligns closely with agentic access design.
What long-lived credentials get wrong operationally
Long-lived credentials are not only a theft problem, they are an operational design problem. They tend to survive ownership changes, environment changes, and workflow changes, so the credential outlives the decision context that justified it. In agent systems, that means a token can remain useful long after the underlying prompt, plan, or approval is obsolete.
They also make rotation harder in practice. If an agent depends on one durable secret across many tasks, teams delay revocation because they fear breaking automation. That creates hidden coupling, where security teams know the credential is too durable but feel operational pressure to leave it in place. Over time, this leads to secret reuse, broader scope than intended, and poor incident containment.
This is why practical secrets programs emphasise dynamic issuance, expiry, and rotation rather than treating credentials as durable application settings. NHIMG’s Secrets Management Guide and Guide to NHI Rotation Challenges are useful complements when you are designing expiry and rotation for agent credentials.
How to decide what an agent should present at runtime
The practical question is not “Can the agent hold a credential?” but “Does this action deserve fresh authority right now?” If the answer depends on current context, target system, or human approval, the agent should authenticate just-in-time and receive a narrowly scoped token. If the action is low-risk and repetitive, a short TTL with constrained scope is still preferable to a durable secret.
For sensitive operations, re-authentication tied to execution context is stronger than trust established once at session start. That means the credential should reflect the exact task, the exact audience, and the shortest reasonable time window. The more an agent can switch tools, domains, or data sets, the less acceptable it is to let one long-lived credential follow it everywhere.
That approach is also consistent with OAuth-based delegation patterns, including audience restriction and token exchange. Where agents need to act on behalf of something else, token handling should preserve scope boundaries rather than flattening every action into one reusable bearer secret.
Risk and Threat Considerations
Long-lived agent credentials increase the chance that a single leak, misuse, or overprivileged token becomes a durable foothold. Once a bearer credential is copied, replayed, or reused outside the intended task, the attacker may be able to act with the agent’s authority until the secret is found and revoked.
Failure mechanism: A persistent credential is exposed through logs, code, memory, browser storage, or an integration boundary, then reused across tasks or environments because it is still valid and still trusted.
Impact: The resulting compromise is harder to contain, because the same credential can enable repeated access, obscure attribution, and expand blast radius across sessions, systems, or automation paths.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and OWASP Agentic AI Top 10 address the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-07 — Long-Lived Secrets | Agent tokens should expire quickly rather than remain valid indefinitely. |
| NHI-09 — NHI Reuse | Reusing one credential across tasks weakens attribution and expands blast radius. | |
| NHI-05 — Overprivileged NHI | Long-lived tokens often carry more access than a single task needs. | |
| Recommendation — Prefer short-lived credentials and rotate or revoke durable secrets promptly. Avoid reusing the same secret across sessions, tasks, or environments. Scope agent credentials to the minimum permissions needed for the task. | ||
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Agent authority should be time-bound and context-bound to limit abuse. |
| Recommendation — Bind agent privileges to the current task and revalidate sensitive actions. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Credential lifetime, rotation and revocation are central to this question. |
| Recommendation — Set short credential lifetimes and revoke authenticators immediately on suspicion. | ||
Practitioner Guidance
What to prioritise: Give each agent the minimum token lifetime that still lets it complete the task without unnecessary interruption. If a workflow needs repeated access, redesign the workflow before extending token duration.
What to verify: Confirm that each token is scoped to a single audience, a single purpose, and a bounded expiry. If the same credential works across unrelated tools or environments, it is already too broad for agent use.
Common mistake: Treating a long-lived secret as “easier to operate” because it reduces reauthentication prompts. That convenience usually just moves the cost into incident response, revocation, and forensic ambiguity.
Practitioner takeaway: For agents, short-lived tokens are the safer default because they keep authority aligned to execution, not memory. Durable credentials should be the exception, not the operating model.
Related resources from NHI Mgmt Group
- How can organisations govern AI agents that use service accounts and tokens?
- Should organisations use short-lived tokens instead of standing credentials in CI/CD?
- When should organisations replace long-lived NHI credentials with short-lived ones?
- What breaks when agents use long-lived API keys or shared credentials?